china says it developed the high-speed train line on its own based on technologies used by japan's bullet train. the launch of the new service expands china's high-speed railway network to more than 9,300 kilometers. officials plan to extend the network to 16,000 kilometers by 2020. the chinese government temporarily suspended construction of high-speed train lines after 40 people died in a two-train collision last year. but it has resumed construction with the aim of helping correct economic disparities between england and the coastal areas, and shoring up the economy. strong concerns remain in china about the safety of high-speed railways. >> translator: it's good to be fast, as well as safe. but safety should be given priority. >> reporter: railway ministry officials stress that they will reinforce safety measures. these including limiting maximum speed to 300 miles per hour for the time being, 50 kilometers per hour slower than what the trains are capable of. shun ishibe, nhk world. >>> a suicide bomber has struck a u.s. military base in afghanistan, killing three people. patchari rak